Electrical heater for cooking purposes



Sept. 21, 1937. STRACK ELECTRICAL HEATER FOR COOKING PURPOSES Filed Dec. 19, 1955 3 Sheets-Sheet 1 Inventor: 'e drZcZ, 67/1204 Attorney Sept. 21, 1937. A. F. STRACK 2,093,939

ELECTRICAL HEATER FOR COOKING PURPOSES Filed Dec. 19, 1955 :s Sheets-Sheet 2 A [to/ 712 p 1937. A. F. STRACK ELECTRICAL HEATER FOR COOKING PURPOSES Filed Dec. 19, 1935 3 Sheets-Sheet 3 Patented Sept. 21, 1937 PATENT OFFICE I ELECTRICAL naam roa oooxmo ruarosas Albert Friedrich Strack, Suresnes, France- Application December 19, 1935, Serial No.

In Germany December 24, 1934 8Ciaims.

This invention relates to an electrical heater for saucepans and other cooking vessels of the type furnished on the outer walls, and more particularly on the bottom, with ribs or other projections serving to increase the heat-transfer area. According to the invention, the heater is so arranged that the ribs or other projections on the vessel are accommodated in pockets or recesses formed by electrical heating elements, 1. e., tubes which are composed of a heat-resisting material and have resistance wires incorporated therein, and which radiate the heat from the electrically heated resistance wires with a minimum of loss towards the outside. To form the pockets or recesses adapted to receive the ribs or projections on'the cooking vessel the said heating elements may be superimposed or juxtaposed according to requirements,

in such fashion that the pockets or recesses thus formed correspond in formand disposal with the ribs or projections on the vessel. Conveniently, they may consist of so-called Backer resistances. Several series of heating tubes arranged side by side or superimposed may be connected to form a continuous series. The tubes are secured in suitable fashion to a common supporting plate, where they are connected with the current source. By reason of the invention there is provided an electrical heater for cooking purposes which is very simple in its assembly and its production and at the same time is effective and economicalin use. In the .case of a heater of this kind the period'required for heating. under conditions otherwise the-same,

is reduced by more than one-third as compared with the usual electrical heaters, with at the same time a considerable saving of current.

In one form of embodiment of the invention the heating tubes radiate the ,heat in direct fashion to the ribs or projections on the cooking vessel- In otherv forms of embodiment there maybe provided-an fitting into the pockets or recesses.

, I intermediate plate, which receives the heat from the heating tubes and transfers-the same to the cooking vessel.

The invention will befldescribed more fully with reference to the accompanying drawings, in which Figs. 1 and 2 are a longitudinal section and plan view respectively of one embodimentof an electrical heater according to the invention.

form of horizontal section respec- The ends I of the series 0 and also the ends a and h of the series d and e respectively are passed through a supporting plate 1, to which they are welded. The plate i may be furnished with openings for the passage of air. Preferably the single series are supported by feet k. The heater composed of the heating tubes as described is accordingly supported by the plate 1, which in turn is mounted on an upright outer ring, the upper edge of which is capable of supporting the cooking vessel. The heating tubes or resistance wires respectively are furnished with the requisite electrical connections.

According to Fig. 4, the heater may also consist of simple concentric rings 0, d and e, The heating tubes may be-cf elongated or. oval crosssection, as shown, or also of circular cross-section as in the previous embodiment. These tubes or which form the pockets for reception of the ribs or projections on the cooking vessel, also results in the advantage of a simple method of manufacture and in that of a favorable transmission of the heat by radiation with negligible loss, inas- 'much as merely a small part of the heat is able to escape by way of the supporting plate i and may be additionally reduced by insulation of the feet of the tubes or of the holding plate.

the drawings.- They may also be disposed in straight lines, for example arranged to be parallel to each other or radial, dependent on-the form and arrangement of the ribs or projections on the bottom or the side walls of the cooking vessel.

In the form of embodiment according to Figs.-

IThe construction of the heater from tubes, 4

The pockets formed by the heating tubes do, not require to be annular in formas shown in- 6 to 9 the transmission of the heat from the tubes n to the ribs 0 on the vesseltal res place indirectly by means of the correspondingly constructed,

plate m carrying the. heating rings. Theserings or tubes n are carried on the under side of the plate m by rib-like abutments p which, after anplication of the rings 1:, are bent into a form side of the plate in other fashion. on the upper side of the plate there are provided ribs 1;, which form the pockets 1' for reception of the ribs on the cooking vessel. In this connection the 5 ribs q may have any desired difierent disposal in relatidn to the heating tubes 71. For example, as shown in the drawings, the ribs q may be dis posed in a straight line and situated parallel to each other, corresponding with the ribs 0 on'the cooking vessel, whilst the tubes may be of spiral form.

The heating tubes n transfer their entire heat to the plate m, which moreover is also well insulated downwards and consists of a good conductive metal, such as aluminum'or copper, so that the heat acquired by the plate passes in its entirety from the walls of the pockets 1 to the ribs or projections 0 on the bottom of the vessel introduced into the pockets.

Since in the arrangement according to the invention the transfer of the heat to the bottom of the cooking vessel takes place primarily by radiation, there may conveniently be provided between the walls of the pockets and the ribs air spaces, as a result of which a rubbing action between the ribs and the walls of the pockets is avoided. In consequence it is also possible to employ in respect of the ribs on the cooking vessel, particularly if these consist. of aluminium, oxidized or dark-colored surfaces, which possess better powers of radiation than light or bright surfaces. These surfaces are not subject to wear, as owing to the air spaces there is no rubbing action between them.

If desired, the heater may also be composed of exposed electrical heating resistances, that isto sayof resistance elements having no covering tubes. These then require to be insulated, and should have no metallic contact with the cooking suitable air spaces or the cooking vessel may be composed wholly or in part of a non-conductive material. The resistances should preferably be protected against impact or against contact with liquids.

If it is desired to make the vessel and the heater integral, the tubes may be embedded in direct fashion in the bottom of the vessel, in which case the tubes are supported by correspondingly shaped ribs on the vessel.

What I claim as new and desire to secure by Letters Patent is:

'1. In an' electrical heater for cooking vessels having external projections for increasing the heat transfer, heating elements comprising heatresisting tubes and resistance wires incorporated therein, the said elements being arranged to form recesses for reception of the projections on the said-cooking vessel, and the width of the said recesses being greater than the thickness of the said projections to provide for clearance between the said projections "and the said heating elements. 2. In an electrical heater for cooking vessels having external projections'for increasing the cesses for reception of the projections on the said heat transfer, superimposed series of concentrically disposed heatingelements arranged to form recesses for reception of the projections on the said cooking vessel, the single series of said elements being interconnected, and the width of the said recesses being greater than the thickness of the said projections to provide for clearance bevessel, for which purpose there may be provided tween the said projections and the said heating elements.

3. In an electrical heater for cooking vessels having external projections for increasing the heat transfer, concentric series of superimposed heating elements arranged to form recesses for reception of the projections on the said cooking vessel, the single series of said elements being interconnected, and the width of the said recesses being greater than the thickness of the said projections to provide for clearance between the said projections and the said heating elements.

4. In an electrical heater for cooking vessels having external projections 'for increasing the heat transfer, heating elements constituting elevations on the said heater arranged to form recesses for reception of the projections on the said cooking vessel, and a plate supporting the said 'heatingeleme'nts, the ends of the said elements porting the said heating elements, the elements constituting the wall of each recess forming a continuous series and the ends of the said series being connected with the said plate, and the width of the said recesses being greater than the thickness of the said projections to provide for clearance between the said projections and the said heating elements. I

6. In an electrical heater for cooking vessels having external projections for increasing the heat transfer, heating elements arranged to form recesses for reception of theprojections on the said cooking vessel, a ring surrounding the said elements and supporting the said cooking'vessel peripherally, and a plate within the said ring supporting the said elements from below, and the width of the said recesses being greater than the thickness of the said projections to provide for clearance between the said projections and the said heating elements.

'7. In an electrical heater for cooking vessels having external projections for increasing the heat transfer, heating elements arranged to form recesses forreception of the projections on the said cooking vessel, a supporting plate, and feet supportlngthe said elements on the said plate, and the width of the said recesses being greater than the thickness of the said projections to pro- ,vide' for clearance between the said projections and the said heating elements.

8. In an electrical heaterv for cooking vessels having external projections for increasing the heat transfer, heating elements constituting elevations on the said heater arranged to form recooking vessel, the width of the said :recesses being greater than the thickness of the said proments.

- ALBERT FRIEDRICH STRACK. 

